FRIDAY, May 4 (HealthDay News) -- Young autistic children have difficulty recognizing ordinary words, and their brains become overtaxed as a result, according to a University of Washington study.

"Rather than becoming an expert in recognizing words, their brains slow down. Because these children can't distinguish what should be a familiar word, their brains work too hard, and they are unable to focus on new words. When they can't understand a word, they miss everything else that follows in a sentence," Patricia Kuhl, co-director of the university's Institute for Learning and Brain Sciences and an expert in how infants acquire language, explained in a prepared statement.

Her team was scheduled to present the findings Friday at the International Meeting for Autism Research in Seattle.

The researchers used sensors to record the brain waves of children between 19 and 30 months of age as they listened to familiar words (dog, cat, ball, book) and unfamiliar words (bide, pint, rate, verb).

The pattern of brain activation in typically developing children showed markedly different responses to familiar and unfamiliar words. Their brain activity when hearing both types of words was centered in the temporal lobes of both hemispheres of the brain.

Autistic children showed no difference in brain response when hearing familiar and unfamiliar words, which means they were unable to differentiate between the words, the researchers said. Brain activity when hearing the words was more diffuse and not centered in the temporal lobes. This indicates that they were using more of the brain in an effort to understand the words, the team said.

The two groups of children also listened to recorded words that were played backwards. The brains of the typically developing children responded as if they were hearing something entirely different from other types of words. The autistic children's brains showed a similar pattern.

"One of the puzzles of autism is the variability of children with it," said Kuhl, a professor of speech and hearing sciences. "We believe the highest functioning autistic children have some recognition of phonemes (the basic sounds of language). And this new study shows autistic toddlers can differentiate between backward words, which are not characteristic of a language, and real words. So, some learning has gone on."

This study is part of research to understand why language disorders are a characteristic of autism.

More information

The U.S. National Institute of Neurological Disorders and Stroke has more about autism.